Conventionally, a brightness enhancement film (BEF) is widely used in a light module to concentrate a light beam generated by a light source. Specifically, the brightness enhancement film (BEF) is applicable to the display monitor to meet the requirement for higher luminance or to the display supplied with a battery set. Such an application attempts to reuse the light outside the visual angle of the user by reflecting the light beam along the direction of the user in order to increase the usage efficiency of the light source.
The brightness enhancement film (BEF) is composed of prism sheets for centralizing the light beam and the prism sheets are arranged by an array of prisms in single direction. The arrangement of the array prisms is regular and monotone. Since the array prisms are only positioned in a simplex direction, the visual angle of the user cannot be properly changed to meet the requirement of the display standards. In addition, the availability of the concentration of the light beam is decreased due to the regular arrangement along single direction, thereby downgrading to the usability of the light module. Consequently, there is a need to develop an optical adjusting apparatus for solving the aforementioned problems.